It featured a story about nine people, including three IRA men, who were killed at a border checkpoint in 1972.

He later described the article as "a useful prop to demonstrate to all the European leaders the extent to which the concerns about the re-emergence of a hard border and the possibility of a return to violence are very real".

But Rev Dr David Clements, who lives in Carrickfergus, said the Taoiseach's actions have caused concern among families who experienced terror on their doorstep.

His father William, a reserve constable, was murdered in an IRA attack on Ballygawley RUC barracks in 1985.

"I am a few years older than Leo Varadkar and I can remember a hard border," said Mr Clements.

"In the 1970s I lived near it in the village of Ballygawley. My dad was a Methodist local preacher and regularly he went across the border on a Sunday evening to preach at Monaghan Methodist Church.

"Often I went with him. We had no trouble travelling south. On the way back, however, there were often long delays, sometimes an hour or two.

"This had nothing to do with us importing a joint of meat from the best butchers in Monaghan. It had everything to do with the vicious terrorist campaign waged by the IRA."

Others who previously experienced the threat and violence of the IRA have also spoken out.

Former Ireland rugby player Trevor Ringland was diverted away from the carnage of a car bomb which exploded close to the border in April 1987, killing senior judge Lord Justice Maurice Gibson and his wife Lady Cecily.

Three team-mates - Nigel Carr, Philip Rainey and David Irwin - nearly died after the judge's car hurtled towards their vehicle.

He said: "There is no justification for using violence to try and bring about constitutional change on this island.

"It's extremely important that those in positions of leadership, such as the Taoiseach, are very careful with their language.

"We don't want to see anyone over-hyping the situation that could in any way give any respect or credibility to the use of violence.

"It (a custom check) is purely a business arrangement.

"There's no block in people crossing the border whatsoever, because Ireland is not in Schengen (area border arrangements), so that will continue as normal. As will the Irish rugby team and Irish hockey team."

The border runs for over 300 miles from Lough Foyle to Carlingford Lough.

John Sproule's 23-year-old brother Ian was killed by the IRA near Castlederg in 1991.

He said he was "sickened" by Mr Varadkar's comments.

"It's so disappointing," he said.

"Instead of trying to work this out by democratic means, he should be trying to do the best for the Republic and Northern Ireland instead of scaremongering.

"The photograph of the bomb put shivers up my spine.

"As a leader, he should be encouraging people to do the right thing."

Diane Woods lives in Enniskillen.

Her aunt and uncle were shot in their home by IRA gunmen in September 1972.

Tommy and Emily Bullock lived close to the Fermanagh and Cavan border. Tommy was a part-time member of the UDR.

"It's absolutely ridiculous," said Ms Woods of the Taoiseach's comments.

"I can't figure out any reason why there should be a return to violence.

"I think he's just trying to make people along the border feel anxious and don't think there's any foundations in it."

Sam, who withheld his surname because of fears that he could be targeted, lives in Newtownhamilton in south Armagh.

He has worked with members of the Kingsmill families who lost relatives in a shooting massacre on January 5, 1976, when 10 Protestant workmen were killed.

Sam said Mr Varadkar's comments this week have "scared" him into believing that violence may restart in the event of a hard border.

He described the Taoiseach's choice of words as a "shame and a disgrace" that have made him feel "vulnerable".

"It sounds like a warning and I can tell you one thing - we wouldn't want it to be like it was before," he said. "Victims are being retraumatised. It brings everything back to them and scars them. I'll never forget what happened to me and my family while living for years under severe threat.

"It would scare the life out of me for this to start up again. Luckily enough we came through it."

The Tanaiste said concerns about the potential to destabilise the island's "very precious peace" were real, and reflected the fears of people living on the border.

Mr Coveney defended Mr Varadkar, insisting he dealt in facts. "We are not trying to scaremonger here, what we are trying to do here is protect a very precious peace and normality on the island of Ireland," he told BBC Radio Ulster.

He added: "If you speak to families living on the border area they will talk in very emotive terms about their fears of the re-emergence of that border infrastructure and it's important to be honest about that.

"It doesn't suit some people's political narrative, it certainly doesn't suit people who advocate for Brexit because this is a very awkward and difficult issue for people to deal with, but it's the truth."